unit 2 ( technique in planning and pre-construction of roadwork )

TECHNIQE IN PLANNING AND PRE-CONSTRUCTION OF ROAD WORKHighway Engineering C3010 /

UNIT2

i

TECHNIQUE IN PLANNING AND PRE-CONSTRUCTION

OF ROADWORK

OBJECTIVES

General Objective

To understand the planning activities and all pre-construction works

Specific Objectives

At the end of the unit you should be able to :-

describe the planning objective. state the procedures to identify a new road. state the procedures for site investigation describe the method of site exploration. describe the survey works.

UNIT 2UNIT 2


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TECHNIQUE IN PLANNING AND

PRE-CONSTRUCTION

ROADWORKS

2.0 TECHNIQUES IN PLANNING AND PRE-CONSTRUCTION

ROADWORK.

A construction of a new road must under go an extensive planning,

accurate land surveying and economic planning.

2.0.1 Planning Requirements

A modern highway construction would include:-

1. A collection of a tabulated information on the existing transportation

facilities in the area.

2. The determination of the general inter-relation of all branches of the

transportation system and their effect on each other.

3. The determination of the adequacy or otherwise of the existing

facilities as per present needs and the improvement and extension

of these facilities for anticipated future needs for a certain period.

4. Methods of financing the projects and the duration of the

construction.

5. An estimation of construction and maintenance.


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Any highway planning study can be sub-divided into :-

1. Road inventory study.

2. Traffic studies.

3. Economic planning studies.

4. Financial planning studies.

2.0.2 Preparation and Planning Scheme of a New Road.

Planning expertise, evaluation on survey work, knowledge

on geology and experience on civil engineering area are essentially

needed in constructing of a new road. The traffic needs, the

purpose on planning at certain route and approximate cost thus

become very vital information to be considered before constructing

a new road.

The synopsis of procedures that is used for identifying,

planning and constructing a new road are listed in the following

page. However, not all new roads follow these procedures. Some of

the procedures are valid for certain terms and conditions only.

Below is set of procedure that is used for identifying,

planning and constructing a new road. The procedures are;

1. Identify the problem in traffic congestion, accident and

environment by making a research on transportation and

problematic areas.

2. Identify the maintenance and new construction work needed.

3. Identify the organization and Ministries that are responsible with

the construction work such as JKR, TNB etc.


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4. Collect the information for briefing.

5. Prepare the following plans: -

a. Topography plan.

b. Usage land plan.

c. Geology plan.

d. Agriculture area plan.

e. Domestic plan.

f. Traffic flow plan.

g. Town Consult planning document.

6. Draw a temporary layout sketch and include related

suggestion.

7. Get information on;

a. Junctions.

b. River and drainage.

c. Survey information.

d. The latest traffic data.

e. Ground Level.

8. Prepare a detailed layout with consideration to environmental

impact.

9. Make a valuation.

10.Choose the best road to be constructed. However, the

alternative road should be equally prepared in the planning.

11.Negotiate with other related group such as :-

a. Ministry of Science and Environment.

b. Ministry of Transportation.

c. Water Board, Forestry Department, Telecom Company

d. National Museum.

e. Railway Station.

f. Geology and Mineral Department.

12.Present a report on the entire technical problems.


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13.Analyze the problems faced by the public.

14.Prepare the preliminary report based on the above information

and submit it to the planning division.

15.Wait for the outcome or result.

a. If it is acceptable, draw a road design at 1 : 2500 scale

and proceed to the particular ministry.

b. If it is unacceptable, it needs to be revised thoroughly or

it will be cancelled.

16.Proceed with the following: -

a. Start planning the main task (the identified road).

b. Start planning the alternative roads.

c. Start purchasing the important materials.

17.Get the information from the public on the suggested road and

the other roads involved. Set a panel that consists of external

lawyers and other professionals to conduct a survey.

18.Submit the report to the respective Ministry and wait for the

approval.

19.Prepare the financial report based on the cost benefit analysis

to determine the advantages will bring to the public.

20.Advertise a tender notice and the selected contractor will then

need to prepare and submit the quotation of the contract plan

and document.

21.Accept the tender and start the construction work.

There are 3 stages in planning the construction of a new road :-

1. Stage 1 - Prepare a preliminary report.

2. Stage 2 - Submit the preliminary report.

3. Stage 3 - Finalize the report.


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2.0.3 Stage 1- Preparing a preliminary report.

In this stage, it includes all the preliminary reports and

information that are received during the ensuing stage (refer to

2.0.2, Procedure 14). They are: -

a. Traffic surveying work.

b. Evaluation on the information and planning. Consider

suggestion if there is another useful choice.

c. Design using 6” : 1 mile scale.

d. Budget of the construction and its advantages.

e. Identify the certain road.

f. Report on the alternative road, which includes the

topography, geology and traffic flow, soil consuming and

historical places.

g. Obtain cooperation from the related group such as town

council and state government.

h. If the project is over budgeted the ministry must be inform

and no further work shall be proceed.

2.0.4 Stage 2 - Submitting the preliminary report.

In the preliminary report, it explains about the proposal and its

alternatives of the identified project. It then is submitted to the

person in-charged to obtain permission. However, the following

questions need to be considered.

a. Are the suggestions fulfilled the planning needs at the

national level.

b. Are the advantages accepted?


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c. Are the suggested solution accepted in term of political or

environmental aspect.

While the preliminary report is being studied further, other

experiments should be done such as:-

a. Further soil investigation.

b. The plan preparation on the new road and other related

roads. Report and work are to be prepared. It will only be

submitted if the preliminary report is accepted.

2.0.5 Stage 3 - Finalizing the Report

a. When the preliminary report is accepted, prepare the

road plan with 1:2500 scale.

b. When the final report is completed, submit it to the Head

Quarter for approval. Here, a right budget and

advantages of the project shall be included for approval

purposes.

c. After the costing and advantages valuation are done, this

final report will be submitted to the responsible person to

start off the construction work.

d. If there is no protest from the public or other parties in

fact, the tender will be offered and the selected

contractor. Then, all the construction works will start.

e. If there is a protest, a committee member will be set up

for further investigation.


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2.0.6 The content of the Preliminary Report

The preliminary report which includes the plan must contain the

following aspects:-

a. The existence situation – which is on physical shape and

scheme objective of the existence road.

b. The traffic situation – based on the latest data (not more

than 3 years). A report should include content the total of

traffic user.

c. The alternative roads, which include the costing,

advantages and the environmental impact.

d. Road classification – identify the road classification that is

to be built; highway or ordinary road.

e. Negotiation on the report and the result.

f. Budget the total of roadwork cost, bridges work and

earthwork approximately 20% from the previous budget.

The cost report should comprise the following:

Roadwork:-

- Site clearing cost.

- Earthwork cost.

- Pavement construction and road shoulder work

cost.

- Road furniture work.

- Facilities service work.

- Contingency stretch cost.

g. Valuation is to see the economical aspect of the project.


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h. Enclosed plans – plan with 6”:1 mile scale is used for

new scheme. For the city or village area a bigger scale is

used. Plan must show the following:-

a. The plan of the approved alternative roads.

b. The type of junction and its location.

Avoid using the existence plan. Beside the, the activities

which would be included in the planning and pre-

construction road work are as follow:

1. Site investigation.

2. Survey works and setting out.

3. Site clearing and top soil deletions.

4. Earth works.


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TEST YOUR UNDERSTANDING BEFORE YOU CONTINUE WITH THE NEXT

INPUT

1. State the planning objective of planning in executing a new road

development.

2. State four other activities in planning and pre-construction roadworks.

a.

b.

c.

d.

ACTIVITY 2 A

Question


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1. The objective of planning is to provide a highway system which

would give maximum transportation facilities at a minimum cost.

2. The other activities in planning and pre-construction roadworks be

as follows :

1. Site investigation.

2. Survey works and setting out.

3. Site clearing and top soil deletions.

4. Earth works.

FEEDBACK ON ACTIVITY 2 A

Answer


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2.1 SITE INVESTIGATION

Road structures are the structure which is supported by the ground.

The interaction between the structure and the soil beneath it is complex,

and therefore knowledge of the site and soil condition is important.

2.1.1 Procedures of the investigation

2.1.1.1 Compact sites

In the case of compact sites for road structure, the

investigation requires deep and closely speed borings. The

actual number and position of borings depend on the types

of structure and nature of sites. However, the number of

bore hole should be such as to given a clear picture of all

significant variations in the soil over the site, and the depth

of such bore hole should be such as to reach all strata

likely to influence the stability of the works.

2.1.1.2 Method of site exploration

When discussing the procedure of the investigation,

reference is made to borings as a means of the

investigation. This is perhaps it is the most common

method of site exploration, but certainly not the only one.

Considering new works, from the very small to the very

large contract, a general guide to exploration would be as

follows:

1. Small works- trial pits up to 3m deep.


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2. Medium to large scale works – borings up to 30m

deep

3. Very large scale works – a combination of deep

boring, pits and insitu examination from heading and

shafts.

It must be noted that the above is only guide: the

detailed methods of exploration would depend on the types

of the construction and the site involved.

a. Trial pits

This is the cheapest form of exploration in shallow

depth; above 3 m deep the cost increases rapidly compared

with boring. The main advantage is that soils and rocks can

be exposed and examined insitu. This method shows

changes in strata much more clearly than by boring. The pits

are dug out either by local labour or by a small tractor

mounted excavator. The plan size of a pits depends on

method of excavation, but approximately 1.2 x 1.2 m and

should be dug at distances 20m apart in either direction.

Problem occurs in water bearing soils, particularly

sands, and therefore the economies of shoring and pumping

pits may outweigh the savings gained against specialist

borings. In dry condition these pits are particularly valuable

since they allow hand cut sample to be taken, thereby

minimizing the disturbance of the sample and maximizing

the condition for accurate testing. Deeper trial pits maybe

used for investigation of rock fissures or to explore layer of


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weak rock which cannot be removed intact in normal boring

operations. Such deep pits are costly to construct and would

be used only a large scale exploration. Trial pits are the best

method of exploring back filled areas and side overlain by

variable natural deposit.

b. Borings

All boring should be should be spaced sufficiently

closed together to prevent false deduction concerning the

uniformity of horizontal strata. The deeps of boring will be

determined by the type of loading involved but account must

be taken of any slope in the strata and variation in their

thickness. In particular, when boring through glacial

deposits, care must be exercised to insure that borders are

not mistaken for bedrock.

There are three main factors which govern the depth

of exploration:

1. The depth to which the soil is to be significantly stressed.

2. The depth to which weathering is likely to affect the soil.

3. The depth at which impermeable strata occur.

c. Wash Borings.

The soil is loosened and removes from the bore hole

by mean of a strong jet of water or drilling mud. The liquid is

jetted through a steel tube which is work up and down the

hole. The liquid disintegrates the soil and carries it up the

annular space between the tube and casing. Wash boring as


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the advantage that the soil is not disturbed by blows of a tool

or shell, but it is limited to soil which do not contain boulders

or large gravels. Mud such as bentonite, allows boring to be

carried out without linings is non-cohesive soils. The soil in it

settled-out state can be dried and use for identification

purposes.

2.2 SURVEY WORK AND SETTING OUT

2.2.1 Preliminary Survey

The preliminary survey consist in running a accurate

traverse line, usually called the Base Line along the route already

recommended as a result of reconnaissance survey, in order to

obtain sufficient data for final location. Similar traverses may also

be run along the secondary routes, if any. The preliminary survey

shall help gather all the physical information which might affect the

final location of the highway. The traverse being an “Open” one,

adjustment cannot be made as in the case of closed traverse so

that in order to ensure some standard of accuracy, certain

precaution especially in the measurement of angels and chaining,

etc., are necessary.

After establishing the Base Line, important topographical

features may also be recorded. These features include swamps,

lakes and any other features which affect the final location and

design of the highway. All the information collected by preliminary

survey work is used in preparing a map, often called the basic plan

or Preliminary Survey Plan.


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The next step after recording all the available details on the

basic plan is to locate the center line of the proposed highway on it.

A number of trial lines are drawn on the plan, avoiding valuable

property, obstruction and difficult areas such as water-logged

areas, etc. Having thus selected the center-line on the plan, the

next step consist in transferring on to the field.

2.2.2 Setting Out

The first task is to establish a Base Line from which the

whole of the road can be set out. The position of this line must be

clearly marked on-site so that it can be re-established at any time.

Setting out was done by plotting the construction boundaries after

being referred from the previous survey on Preliminary Survey Plan

and Base Line. Wooden pact shall be placed at each reference

point and can be easily seen.


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TEST YOUR UNDERSTANDING BEFORE YOU CONTINUE WITH THE NEXT

INPUT

1. State the two methods that are used in soil exploration.

a. ________________________________

b. ________________________________

2. State the three main factors which govern the depth of exploration.

a. _________________________________

b. _________________________________

c. _________________________________

ACTIVITY 2 B

Question 1


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1. a. Trial pits

b. Borings

2. There are three main factors which govern the depth of

exploration:

1. The depth to which the soil is to be significantly

stressed.

2. The depth to which weathering is likely to affect

the soil.

3. The depth at which impermeable strata occur.

FEEDBACK ON ACTIVITY 2 B

Answer


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1. What are the procedures in identifying the construction of a new road.

2. Describe the following aspects: -

a. Preliminary Survey.

b. Setting Out

3. Describe the Trial Pits of soil exploration.

Question


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The procedures to identify a new road include:-

2a. Preliminary Survey

The preliminary survey consist in running a accurate

traverse line, usually called the Base Line along the route already

recommended as a result of reconnaissance survey, in order to

obtain sufficient data for final location. Similar traverses may also

be run along the secondary routes, if any. The preliminary survey

shall help gather all the physical information which might affect the

final location of the highway. The traverse being an “Open” one,

adjustment cannot be made as in the case of closed traverse so

that in order to ensure some standard of accuracy, certain

precaution especially in the measurement of angels and chaining,

etc., are necessary.

After establishing the Base Line, important topographical

features may also be recorded. These features include swamps,

lakes and any other features which affect the final location and

design of the highway. All the information collected by preliminary

Answer


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survey work is used in preparing a map, often called the basic plan

or Preliminary Survey Plan.

The next step after recording all the available details on the

basic plan is to locate the center line of the proposed highway on it.

A number of trial lines are drawn on the plan, avoiding valuable

property, obstruction and difficult areas such as water-logged

areas, etc. Having thus selected the center-line on the plan, the

next step consist in transferring on to the field.

2b. Setting Out

The first task is to establish a Base Line from which the

whole of the road can be set out. The position of this line must be

clearly marked on-site so that it can be re-established at any time.

Setting out was done by plotting the construction boundaries after

being referred from the previous survey on Preliminary Survey Plan

and Base Line. Wooden pact shall be placed at each reference

point and can be easily seen.

.

3. Trial pits

This is the cheapest form of exploration in shallow depth;

above 3 m deep the cost increases rapidly compared with boring.

The main advantage is that soils and rocks can be exposed and

examined insitu. This method shows changes in strata much more

clearly than by boring. The pits are dug out either by local labour or

by a small tractor mounted excavator. The plan size of a pits

depends on method of excavation, but approximately 1.2 x 1.2 m

and should be dug at distances 20m apart in either direction. Trial


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pits are the best method of exploring back filled areas and side

overlain by variable natural deposit.

unit 2 ( technique in planning and pre-construction of roadwork )

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